Age-related changes and nutritional regulation of myosin heavy-chain composition in longissimus dorsi of commercial pigs
Age-related changes and nutritional regulation of myosin heavy-chain composition in longissimus dorsi of commercial pigs
复制标题
商品猪背最长肌肌球蛋白重链组成的年龄相关变化及营养调节
DOI：
10.1017/s1751731113000992
复制
发表时间：
2013-09-01
期刊：
影响因子：
3.6
通讯作者：
Qi, K. K.
中科院分区：
文献类型：
--
作者：
Men, X. M.;Deng, B.;Qi, K. K.
本研究旨在探讨日粮中添加共轭亚油酸（CLA）对商品猪肌纤维类型的影响及其与年龄的关系。试验将25头杂交公猪分为5个年龄组（7、30、60、100和180日龄），30头育肥猪分为2个饲粮组（1组饲喂富含cla的饲粮，1组饲喂对照组，饲喂30 d）。根据MyHC (I, IIa， IIb和IIx) mRNA的绝对拷贝数和最长肌中琥珀酸脱氢酶（SDH）和苹果酸脱氢酶（MDH）的活性，分析了MyHC mRNA的组成（%）。第7 ~ 180天，MyHC I mRNA丰度和SDH、MDH活性呈下降趋势，MyHC IIb mRNA丰度呈稳定趋势，MyHC IIa、IIx mRNA丰度呈上升趋势。第30天，MyHC I和IIb mRNA丰度最低（P < 0.05）， MyHC IIa和IIx mRNA丰度最高（P < 0.05）。CLA组最长肌MyHC I mRNA丰度和SDH、MDH活性均有所提高，压力损失、滴水损失和平均背脂肪深度显著降低（P < 0.01），剪切力显著增加（P < 0.01）。腰眼面积、饲料转化率和肉色均有改善的趋势。这些结果表明，随着年龄或体重的增加，更多的氧化纤维可能转化为糖酵解纤维，而早期发育阶段可能是这种转化的关键阶段。在肥育期，饲粮中添加CLA可提高肉中氧化纤维的比例，从而提高肉的持水能力。研究结果可为肌纤维类型在猪肉品质改良中的应用提供重要依据
The objective of this study is to investigate the age-related changes of and the effects of dietary conjugated linoleic acid (CLA) on muscle-fibre types in commercial pigs. We divided 25 crossbred male pigs into five age groups (7, 30, 60, 100 and 180 days) and 30 finishing pigs into two dietary groups (one fed a CLA-enriched diet and the other fed a control diet for 30 days). We analysed the composition (%) of myosin heavy-chain (MyHC) mRNA according to the absolute copies of each MyHC (I, IIa, IIb and IIx) mRNA, and the activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) in the longissimus muscle. From days 7 to 180, the MyHC I mRNA abundance and SDH and MDH activities presented a decreasing trend, the MyHC IIb mRNA abundance presented a steady trend and the MyHC IIa and IIx mRNA abundances presented an increasing trend. On day 30, MyHC I and IIb mRNA abundances were at their lowest (P < 0.05), and the MyHC IIa and IIx mRNA abundances were at their highest (P < 0.05). In the CLA group, the MyHC I mRNA abundance and the activities of SDH and MDH were improved in the longissimus muscle, whereas pressure loss, drip loss and average back fat depth significantly decreased (P < 0.01) and shear force significantly increased (P < 0.01). Loin eye area, feed conversion rate and meat colour showed some tendency to be improved. These results indicated that more oxidative fibres might convert to glycolytic fibres with increasing age or weight, and that the early developmental stage might be a key stage for this conversion. During the finishing stage, the proportion of oxidative fibres might be increased by dietary CLA supplementation, which may contribute to the water-holding capacity of meat. The results would provide an important basis for the application of muscle-fibre types in the improvement of pork quality